gns3-server/docs/api/examples/controller_put_gns3vm.txt

curl -i -X PUT 'http://localhost:3080/v2/gns3vm' -d '{"vmname": "TEST VM"}'

PUT /v2/gns3vm HTTP/1.1
{
    "vmname": "TEST VM"
}


HTTP/1.1 201
Connection: close
Content-Length: 27
Content-Type: application/json
Date: Thu, 07 Jun 2018 08:13:54 GMT
Server: Python/3.6 GNS3/2.1.7dev1
X-Route: /v2/gns3vm

{
    "vmname": "TEST VM"
}